Insufficient engine power

The power shortage of automobile electronic control engine means that its power is poor. Engine power shortage is a common fault phenomenon in automobiles, it produces many reasons, and involves a wide range of facets.

First, insufficient engine power failure

(a) fault phenomenon

Engine load-free operation of the basic normal, but with load running slow acceleration, uphill weakness, accelerating pedal on the end still feel the lack of power, rotational speed is not high, up to the maximum speed.

(ii) Causes of failure

1. Throttle adjustment is improper, can not open.

2. The air filter is clogged.

3. Fuel pressure is too low.

4. Cylinder is short of fire.

5. Ignition timing is improper or high pressure sparks are weak.

6. Air flow meter or intake manifold vacuum degree sensor, coolant temperature sensor, throttle position sensor fault.

7. The injector is clogged or poorly atomized.

8. The exhaust gas recirculation unit is poorly functioning.

9. The cylinder compression pressure is too low or the timing of the gas is inaccurate.

10. Exhaust gas is obstructed, the inlet manifold vacuum is obviously low when the engine is loaded.

(iii) General steps for fault checking

1. Fault self-diagnosis, check for trouble-free code appears. If you have the condition, use a special diagnostic instrument to read the dynamic Data stream, or to check the data with a multimeter. Sensors and actuators that affect power are: coolant temperature sensor, air flow meter or inlet manifold absolute pressure sensor, throttle position sensor, igniter, injector, etc. Analyze the failure by the displayed fault code or data stream to find the cause of the failure.

2. Step the accelerator pedal to the end to check whether the throttle is fully open. If not fully open, adjust the throttle cable or pedal.

3. Check the air filter for any clogging. If there is a blockage, it should be cleaned or replaced.

4. Check the ignition timing with the ignition timing lamp. In the idle operation after the hot car to check the ignition advance angle, should be 10° 115 ° or in line with the original regulations, accelerating ignition advance angle should be able to automatically advance to 20° 130 °. If the ignition advance angle is not correct at idle speed, the initial ignition angle should be adjusted, and if the ignition advance angle is incorrect, the ignition advance control line and the crankshaft position sensor and igniter should be checked.

5. Check if there is no clear cylinder. Can do single cylinder break fire, oil break test.

6. Check all spark plugs, HV lines, ignition coils. If there is an abnormality, it should be replaced. Ignition oscilloscope can be used to observe the ignition waveform after confirmation.

7. Check the fuel pressure. If the pressure is too low, you should further check the electric fuel pump, oil pressure regulator, fuel filter and so on.

8. Remove the injector and check if the fuel injection is normal. If the fuel injection is not normal or spray oil atomization is bad, should clean or replace the injector.

9. Detect air flow meter, throttle position sensor, crankshaft position sensor, camshaft position sensor, coolant temperature sensor, oxygen sensor, deflagration sensor signal.

10. Check whether the exhaust gas recirculation unit is working properly.

11. Check the gas phase, valve clearance is correct.

12. Check the operating conditions of the intake booster, the variable timing of the gas distribution and the valve lift device.

13. Check whether the exhaust gas is not smooth, three-dimensional catalytic converter is blocked. Check with vacuum gauge and exhaust back pressure gauge, or disassemble.

14. Measure cylinder compression pressure, check valve carbon, dismantle engine and so on. such as the cylinder pressure is too low, the valve spring is too soft, the air distribution cam wear and so on can cause the power drop.

Second, fault diagnosis, elimination of the relevant points

(a) to confirm that the motor vehicle weakness is caused by insufficient engine power

Car acceleration speed is very slow, uphill when the car more slowly phenomenon, do not blame the engine, should pay attention to if the drive system skid or drive System "strike", will make the car speed slow, easy to be misunderstood as the engine power performance is poor. In order to confirm whether the speed of the car is caused by the engine, the following methods can be identified.

1. Lift the car speed on the highway, then suddenly retract the accelerator pedal and push the variable speed handle into the empty gear immediately. If the car by inertia glide distance longer, prove that the car drive and driving part of the "strike" failure. If the glide speed slows down obviously, then the car travels "strike".

2. When the car uphill, according to the conventional shift, should pay attention to whether the engine speed and speed match. If the speed of deceleration is obvious, and the engine speed is very high, it indicates that the drive system skid.

3. For vehicles with traction control systems, the traction control system should be turned off again. If the traction control system is turned off, the car is fully powered, and the fault is in the traction control system, not the engine. For example, traction control system because the sensor is still working and generate sufficient voltage, so at this time there is no fault code, we should pay attention to the noise interference contained therein. The car is equipped with traction control and anti-lock braking system, while the ebcm noise interference is mistaken for the increase in wheel speed. In this way, the ebcm will always give the wheel a certain braking force, so that the driver complained that the car is not enough power. In addition, the Driver Information screen will display "Traction Active", and you can be aware that the car is applying braking.

The cause of the interference signal is that the wheel speed sensor magnet on the positioning is not good, can float up or down or is not good shielding. 4. Heavy load when the engine is weak, in the known automatic transmission failure can also do a stall test to see if the stall speed is too low.

(ii) Analysis of the essential causes of engine power shortage

The poor power performance of the fuel engine is mainly facilitated by the following:

1. Poor air-fuel ratio or insufficient supply.

2. Poor ignition performance.

3. Electronically controlled fuel injection engine, electronic control system malfunction.

4. Improper engine adjustment or assembly, or the engine itself is in poor mechanical condition.

For fuel engines, if the air-fuel ratio of the mixture is improper, the mixture is too thin or too dense, which will affect the engine's dynamic performance. If the mixture is too dense, the exhaust pipe will take black smoke, if the mixture is too thin, it will cause slow combustion, severe when the trachea temper blasting. But if the air-fuel ratio imbalance is not too serious, then the above symptoms are not very obvious. The supply of combustible mixed gas is not enough to be detected by intuition.

The main cause of poor air-fuel ratio or insufficient gas supply is the lack of fuel supply or the obstruction of air supply, so check the oil circuit and air filter.

Poor ignition performance mainly refers to high-voltage spark weak, lack of fire, high-speed heavy load when the fire, ignition is not positive.

Improper engine adjustment or assembly, or the engine itself is poor mechanical condition, mainly mechanical wear or improper assembly adjustment resulting in poor intake, exhaust performance, cylinder pressure drop, such as timing with the wrong teeth, cam wear, valve clearance is not correct, valve carbon serious, valve spring too soft resulting in high-speed operation of the valve floating, Cylinder liner and piston ring wear and so on.

The malfunction of electronic control system refers to some problems caused by the sensor, actuator or ECU of electronic control system, such as fuel injection control, ignition advance angle control, inlet control, booster control, variable gas phase and valve lift program control, variable exhaust controller, etc.

(iii) Inspection of fuel supply conditions

(iv) Inspection of three-dimensional catalytic converters for automobiles

The ternary catalytic converter is located in the center of the lower part of the car and is bolted to the rear tube of the exhaust manifold. The ternary catalytic converter is a monolithic structure, shown in 5-2, which is coated with a catalyst on the grid surface in the center of its exhaust pipe. The role of ternary catalytic converters is to convert harmful gases such as HC, CO and n0x in the exhaust gas into c02,n2, and water vapor.

When the theoretical air-fuel ratio is 14. 7:1, exhaust gas temperature at 400℃~800℃, three-way catalytic converter can most effectively reduce the amount of HC, C0 and n0x in the exhaust gas.

When the engine appears such as failure, such as fire, may lead to the exhaust temperature of more than 1400 ℃, so that the three-dimensional catalytic converter substrate melting, burned three-dimensional catalytic converter. The use of leaded fuel should be avoided, as lead in the exhaust gas is covered on the catalyst surface, preventing the catalytic reaction from being carried out, and the residual fuel in the exhaust gas may also poison the catalyst.

1. Visual inspection. Check the appearance of the ternary catalytic converter. If the shell is found to be squashed, corroded or dented, it should be replaced.

2. When removing the ternary catalytic converter from the vehicle,

Use a flashlight to discharge 15 of its exhaust to see if it is accumulated carbon or lead

Clogging of contaminants.

3. Gently shake the three-dimensional catalytic converter, listen to the internal components have no signs of loosening. If a component is blocked, melted or otherwise damaged, the ternary catalytic converter should be replaced.

4. Functional Testing

(1) at 2500r/min speed of the engine running about 2rain, the three-dimensional catalytic converter heating to the operating temperature.

(2) A surface temperature probe is connected to the exhaust gas population and outlet of the ternary catalytic converter to measure the temperature.

(3) The outlet temperature should be at least 38% higher than the inlet temperature.

(4) If the temperature difference is lower than the specified value, the three-dimensional catalytic converter should be replaced.

(5) Use the exhaust back pressure gauge to detect the exhaust pressure at the oxygen sensor mounting hole or at the carbon monoxide (CO) test tube.

(6) Install the exhaust pressure gauge at the oxygen sensor (or carbon monoxide test tube).

(7) At normal operating temperature, the engine idle speed, the pressure gauge reading should not exceed 8. 6kPa (Some cars do exceed this value, for reference only). Increase the engine speed to 2000r/min, the pressure gauge reading should not exceed 20. 7kPa. If the back pressure exceeds the specified value in either of the two speeds, the exhaust system is obstructed.

(8) Check whether the exhaust system has a compressed pipe, whether the system has thermal deformation or internal muffler failure. If there is no obvious reason for the excessive back pressure of the exhaust system, it is possible that the ternary catalytic converter is blocked. After the test is complete, apply the thread of the oxygen sensor with the anti-adhesion agent before reinstalling.

5. Insufficient power check mnemonics (for reference only)

Motivation is not enough reason, basic check not much to say.

Lack of cylinder failure to find a find, high-pressure fire weak late or early;

Mixed gas low oil pressure, oil pump nozzle filter;

Inlet pressure flowmeter, all kinds of important sensors;

The exhaust gas turbine is not pressurized, and the variable gas distribution is poor;

Insufficient air intake to plug, throttle can not fully full;

Spring too soft valve float, high-speed running force is insufficient;

Valve product carbon cylinder is depressed, it makes sense to disassemble.

Insufficient engine power